Like, did you notice their bellies? Like literal bellies. Look at the underside of a Viper. The bulky boxy shape exists solely to accomodate the one-size-fits all cargo hatch. It is more tastefully integrated into the Eagle, and any ship with a large flat underside (Hauler, Adder), and starting with the Cobra the size of the cargo hatch is so small that the ship doesn't need extra bulk just so that the thing fits on a flat surface.
As a result, the Viper seems to hug the ground when landed, the belly is so close to it that I it doesn't seem able to safely land on uneven ground - compare that with a Cobra which has ample room below it.
The belly is also the reason why the underside doesn't have that elegant triangular shape from front to back - the shape is broken entirely by the boxy bulk around the cargo hatch.

As a result, the Viper seems to hug the ground when landed, the belly is so close to it that I it doesn't seem able to safely land on uneven ground - compare that with a Cobra which has ample room below it.
The belly is also the reason why the underside doesn't have that elegant triangular shape from front to back - the shape is broken entirely by the boxy bulk around the cargo hatch.